Brussels is funding research at Reading University aimed at detecting suspicious behaviour on board aircraft.

A combination of cameras, microphones, explosive sniffers and a sophisticated computer system would give a pilot early warning of any danger. But the work will alarm civil liberties campaigners who fear the growth of the surveillance state.

The Reading team, headed by James Ferryman, has conducted trials of the camera system on a British Aerospace plane and the computer system on a mock Airbus.

Similar systems have been deployed at stations and airports around the world, using CCTV to gather information and software to analyse it.

The software looks out for unusual behaviour or events, such as a case being left unattended or an individual going against the crowd flow.

“What we are doing is extending technology already used at airports and railway stations and placing it on an aircraft,” Mr Ferryman said.

Cameras dotted around an aircraft would look out for the abnormal, such as several passengers entering a lavatory at the same time or individuals seeming agitated.

One option would be to allocate some seats to passengers whose behaviour has already raised concern at the airport, so they could be monitored on board.

Microphones would eavesdrop, listening out for anything which could suggest terrorist behaviour. Inside the lavatories explosives sniffers would detect if a bomb was being assembled.

All this information would be analysed by computer and if it spotted something untoward, the flight deck would be told instantly.

The key to the work is developing software which can spot a genuine threat. “We want to avoid saying that nervous passengers are potential terrorists,” Mr Ferryman said

According to researchers this technology would have thwarted the “underpants bomber” who tried to detonate an explosion on a Christmas Day flight to Detroit.

“It is known that the terrorist was acting nervously in the airport prior to boarding – this could have been picked up with the same automated CCTV technology – and that they spent time in the toilet assembling the components of the explosive,” Mr Ferryman said.

Money for the research has come from the EU Security of Aircraft in the Future European Environment (SAFEE) project. But the aviation industry would be expected to pay for its deployment.

The cost would inevitably be passed on to passengers but Mr Ferryman believes they would accept a small charge to thwart a terrorist threat.

“If I had to pay an extra £5 on an airline ticket and it would go towards a system which would make me safer, I would be happy to do it,” he said.

A Department for Transport spokesman said: “We have no plans to instruct airlines to install this system on their planes.”

The research alarmed Gus Hosein of campaign group Privacy International and a London School of Economics lecturer.

“This is getting out of control. An aeroplane is not a privacy free zone,” he said.